Filtration is the removal of contaminants from a fluid. Fuels, engine oil, transmission and hydraulic fluids and coolants are some fluids that require removal of contaminants that could cause damage to their respective mechanical systems.
Typically, oil filtering devices for automotive engines are embodied as disposable spin-on type filters. Spin-on filters are also used for gasoline filtration at gasoline dispensing pumps. Filtration at gasoline pumps was developed in the 1950's as a quality control feature to reduce contaminants in dispensed gasoline, which contaminants accumulated during handling and storage. Spin-on filters were introduced as an option inside the gasoline pump or on the hand held gasoline dispenser in the early 1960's and have evolved to become a standard feature. These spin-on type filters are each composed of a metal housing enclosing a filter element.
With approximately 400 million spin-on filters manufactured annually, disposal of these filters is environmentally disadvantageous as both a pollution hazard and a volume problem, taking up valuable space in landfills. One solution to alleviate this problem is the recycling of steel components of the spin-on type filters. However, recycling is costly in material handling and requires disposal or incineration of the volatile components absorbed by the filter, and the nonrecyclable contaminated portions of the filter.
Whether in an engine, transmission, gas pump, or in a hydraulic system, a filter adapter is either an integral part of, or mechanically connected to the respective mechanical system. Typically, the filter adapter has a male threaded center post with a concentric flat gasket seal surface. The filter adapter is located and oriented in order for the spin-on filter to have a threaded engagement onto the male center post. A gasket carried by the spin-on filter seals on the flat gasket seal surface of the adapter. Liquid enters the filter in ports that are located between the gasket seal surface and the center post. From the ports the liquid is directed to an outside of the filter element. The liquid is then filtered through the filter media of the filter element, which removes contaminants. The liquid is then diverted through the center section of the filter element and exits the spin-on filter through the center post.
An effective reusable filter assembly would also be configured to screw onto (spin onto) the center post of such a filter adapter.
Some known reusable filter mechanisms have a central threaded port for engagement with the center post of a filter adapter, but which also require a secondary threaded joint to secure and seal the filter housing. U.S. Pat. Nos. 5,342,519; 5,066,391; 5,569,373; and 4,622,136 disclose filter housings which must be unscrewed at the secondary threaded joint to replace the filter element held within the housing.
It would be advantageous to provide a filter assembly which provides a housing with a minimum number of external threaded joints and which would tightly seal the filter assembly to the filter adapter, while providing a convenient means of replacing filter elements. It would be advantageous if such a filter assembly comprised a minimum number of components and was cost effectively produced.